Atholus nitidissimus Desbordes, 1925

dela Cruz, Ian Niel & Ohara, Masahiro, 2023, Revision of the genus Atholus Thomson, 1859 (Coleoptera, Histeridae, Histerinae) from the Philippines with additional records, ZooKeys 1158, pp. 1-26 : 1

Atholus nitidissimus Desbordes, 1925

Figs 5 , 50-53

Atholus nitidissimus Desbordes, 1925: 87 [Leyte Island]; Mazur 1984: 215; 1997: 131; 2011: 105 [catalogued].

Specimens examined.

Two syntypes of undetermined sex housed in MNHN have been examined by N. Dégallier. The following re-description is based on images provided by him.

Diagnosis.

This species is easily distinguished by its almost circular body and absence of sutural elytral striae. Judging by the images of two examined syntypes, this species is clearly distinct in its pattern of dorsal elytral striation, differing from other species by the absence of the fifth or sutural elytral striae. Atholus nitidissimus Desbordes, 1925 (Fig. 5 ) is similar to A. coelestis (Fig. 2 ), albeit it is comparatively smaller in size than other species examined.

Re-description.

Body (Fig. 5 ) length: PEL: 2.15 mm; APW: 0.85 mm; PPW: 1.75 mm; EL: 1.15 mm; EW: 1.95 mm. Body almost circular, convex, and black; tibiae and antennae rufous.

Head: clypeus (Fig. 50 ) slightly crenate on anterolateral margin, apical margin projecting; frontal stria round, complete, and moderately impressed; eyes clearly visible dorsally; mandibles with rounded outer margin curved inwardly; mandibular apex acutely pointed.

Pronotum: marginal pronotal stria (Fig. 50 ) laterally complete, continuous onto the apical angle and behind head; lateral pronotal stria moderately impressed; apical end shortened and bent inwardly; lateral portion rather distant from margin; its basal end obsolete on basal sixth of pronotal length.

Elytra: external and internal subhumeral striae absent (Fig. 5 ); oblique humeral elytral stria lightly impressed on basal third; dorsal elytral striae 1-3 complete; elytral stria 4 present on apical half or shorter; elytral stria 5 either absent or very short; sutural elytral stria absent.

Propygidium and pygidium: propygidium (Fig. 51 ) moderately covered with coarse, round, and shallow punctures; interspaces with fine punctations; pygidial punctures similar to those of propygidium, albeit slightly denser.

Prosternum: anterior margin of prosternal lobe (Fig. 52 ) round; medio-apical end ascending; marginal prosternal stria impressed, shortly interrupted medially; short striae present on both baso-lateral ends; prosternal lobe with several punctures alongside marginal prosternal stria on both sides; entire disk covered with finer punctures; prosternal suture moderately impressed; prosternal process with few fine punctures; lateral sides descending; lateral prosternal striae deeply impressed; basal half of prosternal process narrow.

Meso- and metaventrite: anterior margin of mesoventrite (Fig. 53 ) truncate; marginal mesoventral stria complete; meso-metaventral suture clearly impressed, complete and carinate; lateral metaventral stria moderately impressed, carinate, extending obliquely and posteriorly, united with oblique humeral stria that inwardly extends from metaventro-metepisternal suture; post-mesocoxal stria extending posteriorly, strongly curved along the posterior mesocoxal margin, almost attaining the metaventro-mesepimeral suture; punctation of intercoxal disk of metaventrite similar to that of mesoventrite; longitudinal suture of metaventrite lightly impressed; lateral disk of metaventrite moderately covered with large, round, shallow punctures.

Legs: posterior surface of protibia (Figs 52 , 53 ) flattened and dilated; outer lateral margin with four teeth, topped with minute denticles.

Distribution.

Endemic to the Philippines ( Mazur 2011).

Biology.

Unknown.

Figures

Figures 1 - 6. Philippine Atholus, dorsal habitus 1 A. philippinensis (Marseul, 1854) [IC- 21 - 18] 2 A. coelestis (Marseul, 1857) [IC- 21 - 20] 3 A. torquatus (Marseul, 1854) [IC- 21 - 49] 4 A. pirithous (Marseul, 1873) [IC- 21 - 47] 5 A. nitidissimus Desbordes, 1925 [syntype image] 6 A. bakeri (Bickhardt, 1914) [syntype image, No. 1639]. Scale bar: 1.00 mm.

Figures 50 - 53. Atholus nitidissimus Desbordes, 1925 50 anterior view 51 ditto, caudal view 52 prosternal process 53 habitus, ventral view.